Thinking about getting my first iPhone

Both SMS and MMS are services provided by your cellular telephone service provider. They use the cellular telephone voice network, and for MMS, the image or data part is sent via your cellular data connection.

iMessage is Apple’s internet messaging service. It has nothing to do with your cellular service provider, and yes, iMessage only works between Apple devices. All iMessage needs is an internet connection, whether it be over WiFi, or over a cellular data connection. As long as the data connection is free, iMessage is free since Apple charges nothing for the service itself.

You can also use other popular proprietary internet messaging services on an iPhone, like WhatsApp, Skype, Google Hangouts and so forth.

You can also use iOS/MacOS continuity features to send and receive SMS and MMS on your Macs. The iPhone actually does the sending and receiving since only it can connect to the cellular telephone voice network, but the messages are shared with the Macs via continuity -> Use Continuity to connect your Mac, iPhone, iPad, iPod touch, and Apple Watch - Apple Support

When it comes to SMS and MMS, there is no difference between any make and model of cellular telephone or smart phone. SMS/MMS is old technology, even predating the internet. It is handled entirely by the cellular telephone service providers over their cellular telephone voice network (and cellular data network for the data part of an MMS).

With iMessage, an iPhone user registers their cellular telephone number with their AppleID (Apple’s form of unique personal login ID for all Apple services). That also associates it with any email addresses also registered with that AppleID.

It’s then simple for the system to check the number (and/or email address) being messaged and if it too is registered to an AppleID in the iMessage system, then it gets sent as iMessage. Everything about iMessage uses the internet, not the cellular telephone voice network.

All internet message service (iMesage, Skype, Google Hangouts, WhatsApp) are wholly independent of any cellular telephone service provider’s messaging networks. SMS (as we know it now) dates from the very early 1990’s and actually has its origins in the 1960’s, while the first internet messaging wasn’t until 8-10 years later (AOL being one if the first widely used systems). SMS/MMS are services handled by the cellular carriers and require a cellular telephone, while all internet messaging services are proprietary and handled by company hardware owned by the company offering the service. All any internet messaging service requires is a computing device with an internet connection, which is why they work on tablets, laptops, desktops, smart TV’s...

You should not notice any delay or issues with texting. The only thing you will notice is that when texting to an Apple product it will be blue and anything else will be green. iMessage is used unless it is unavailable for some reason (usually it happens when one person is out of cell range)

The iPhone sending doesn’t “know” the other person actually has an iPhone (or iPad or Mac). The iMessage system knows whether the cellular number or email address being sent to is registered to an AppleID in Apple’s iMessage system.

Its really not terribly different than the carrier based SMS system looking up the cellular number your send an SMS to and routing the message to that cellular telephone. The phone number is register with a carrier somewhere and associated with a texting plan. The system just determines that and routes the message.

Some people need more than 64gb. I have a 256gb but I am not even using 64gb. It is all up to the individual needs of each person. iCloud is available but it is not your primary storage but a backup and does not store every single thing. iCloud backups can be set to do auto magically but you should also manually back up your device to your computer (which would store every single thing.

Go here - Set up iCloud Drive - Apple Support

and here - iCloud Drive FAQ - Apple Support

and here - Set up iCloud on your iPhone, iPad, or iPod touch - Apple Support

These links should have all the information you are seeking about them.

There is a point of confusion regarding iCloud storage and iCloud backups; they are actually not related.

You can set up your phone to back up to iCloud every night automatically. If you do this maintains a copy of most of what is on your phone that can be restored to your phone if you need to recover something that you deleted, or if your phone crashes, or if it has to be repaired, or to the replacement if your phone is lost or stolen. But it is one “object” that replaces everything on your phone, you can’t access it selectively.

iCloud Sync is completely different. You can choose to sync most data on your phone to iCloud. This is real time or near real time, and the data synced can be accessed on other devices that share the iCloud account and much of it can be viewed and managed with a web browser. It’s important to realize that iCloud Sync is a syncing service, not an archiving service. If you delete an item that is synced (like a photo) from your phone it will be removed from iCloud and from all devices that sync to iCloud. Items that can be synced to iCloud: Mail settings, contacts, calendars, reminders, notes messages, Safari browser settings, news settings, Stock app settings, Health settings, Home automation settings if you use Apple Home, Apple Wallet settings, Game Center, Siri settings, Keychain (Apple’s password manager). Plus app data including most document types such as word processing files, spreadsheets, presentations.

There is some interaction between Sync and Backup - essentially, anything that is synced is not included in an iCloud backup, because that would be redundant.

First, iCloud Drive was just an app to view and manage files in iCloud. And it doesn’t exist any more as it was replaced with the “Files” app.

The only thing truly backed up in iCloud is the iCloud backup file. Everything else uses iCloud to synchronize files across your devices. So photos and videos do live in iCloud but also are on your devices. Changes made on any device are reflected in iCloud which then sync’s those changes across all devices. The same thing happens for contacts, notes in iCloud, messages in iCloud.

But what icloud is not is independent archival storage. So if you delete a photo or contact or note on your device, it will be deleted in iCloud.

You can of course not use iCloud photos (I never have) and simply transfer pictures to a computer hard drive for backup and archiving, just as you can with any digital camera.

Apps themselves are not backed up or stored in iCloud. They are downloaded from the App Store as needed. An iCloud backup includes the data associated with your purchased apps, and restores that after downloading and installing the App itself from the App Store during a restore operation.